A microbial fuel cell (MFC) is an electrochemical device that converts organic substrates into electricity through the metabolism of anode-respiring bacteria (ARB). ARB oxidize organic substrates and then complete respiration by transferring electrons to the anode via extracellular electron transfer (EET). Many MFCs are in macro-sized forms that serve as prototypes of large power sources or wastewater treatment technology. Micromachined or microelectromechanical systems (MEMS) MFCs have been explored for use as portable power sources as well as platforms for behavioral studies of ARB.